Delhi's air quality remains in the "severe" zone with an AQI of 409, prompting Grap-III restrictions, including a ban on certain vehicles

GRAP stage 3 will come into force at 8am on Friday. The Delhi government announced that classes for primary schools will be shifted to online.

In a repeat of what occurs every year, Delhi is engulfed by toxic smog as air quality remained in the "severe" category at the onset of winter in the national capital, media reports said.